Question

An inventor claims to have devised a closed cyclic engine which exchanges heat with cold and hot reservoirs at 25 and 350 ◦C, respectively, and produces 0.45 kJ of work for every kJ of heat extracted from the hot reservoir. Is this claim believable?

Answer 1

Explanation:

The given data is as follows.

$T_{c} = 25^{o}C$,  $T_{h} = 350^{o}C$

Work produced per kJ of heat extracted from hot reservoir = 0.45 kJ = Efficiency

If the device is Carnot cycle then its efficiency will be maximum and its value will be equal to $[1 - (\frac{T_{c}}{T_{h}} )]$

Using this relation we will calculate the efficiency as follows.

                 Efficiency = $[1 - (\frac{T_{c}}{T_{h}} )]$

                        = $1 - (\frac{25}{350})$

                       = 0.928

Hence, it means that this type of device is possible and the claim is also believable.